This proposal will allow development of a robust, accurate, and validated software package for highly automated assessment of arterial flow mediated dilatation (FMD) from ultrasound images and image sequences. A commercially available software package with known behavior and assessed accuracy will become available for non-invasive assessment of endothelial dysfunction, one of the earliest indicators of cardiovascular disease. Assessment of FMD requires accurate determination of baseline artery diameter as well as continuous identification of diameter changes after obstructing the blood flow for a period of several minutes. Brachial arterial ultrasound is currently utilized but the developed methodology will be applicable to all peripheral vessels. The overall aim of the proposed research is to develop an automated method for analysis of arterial ultrasound images and image sequences. In addition, new morphological and functional indices related to FMD will be developed that would be potentially useful as early measures of the atherosclerotic process. The specific aims are to: 1. Develop a practical, robust, and accurate method for automated analysis ofarterial ultrasound image sequences. 2. Evaluate its accuracy and reproducibility in clinically acquired image data sets. The proposed methodology has the potential to identify subjects who are destined for atherosclerotic occlusive vascular disease. PROPOSED COMMERCIAL APPLICATIONS: The proposed software package will first be used by researchers studying endothelial function. Later, the software will become a low-cost tool for screening of patients to identify subjects with impaired endothelial function and will be located in almost every family practice office. While more than 6,000,000 U.S. patients have symptomatic coronary artery disease, many more adults have some degree of atherosclerotic narrowing of their coronary arteries. In 1991 stroke affected approximately 500,000 people, killing more than 143,000; peripheral vascular disease resulted in 267,000 hospitalizations and 42,000 deaths. The identification of high-risk individuals with subclinical disease is of major importance if preventive measures are to be instituted.